1. Field of the Invention
The present invention relates in general to a watercraft, and in particular to a propulsion system for a watercraft.
2. Description of Related Art
Personal watercraft have become popular in recent years. Jet propulsion units commonly power these type of watercraft and include a motor driven impeller. The impeller operates within a water duct of the jet propulsion unit. The impeller draws in water through a water intake opening on the underside of the watercraft's hull and into the intake duct. The impeller thence compresses the water and forces it through a stationary discharge nozzle to form a jet of water. This water jet propels the watercraft.
A steering nozzle mates with the discharge end of the discharge nozzle and redirects the water jet stream for steering movement of the watercraft. For this purpose, the steering nozzle commonly rotates about at least a vertical axis and is controlled by a handlebar assembly of the watercraft.
Prior watercraft designs have attempted to minimize the vertical distance between the impeller and the water inlet opening in order to improve the performance of the jet propulsion unit. Pump inefficiencies can result when a substantial portion of the impeller's work goes to drawing water up into the water duct, as opposed to using more of that energy to increase the pressure of the water flowing into the discharge nozzle. The vertical rise of the intake duct therefore has generally been kept small by placing the impeller close to the hull underside. In this position, an impeller shaft, which drives the impeller, often slopes downward in a fore-to-aft direction. The resulting water stream exiting the discharge nozzle projects downward into the body of water in which the watercraft is operated.